| Trichocereus macrogonus | |
|---|---|
 | |
| Trichocereus macrogonus var.pachanoi – the tall cactus in the mid-foreground, in its natural habitat in Peru | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Order: | Caryophyllales |
| Family: | Cactaceae |
| Subfamily: | Cactoideae |
| Genus: | Trichocereus |
| Species: | T. macrogonus |
| Binomial name | |
| Trichocereus macrogonus | |
| Synonyms | |
Of the species:[2]
OfT. macrogonus var.macrogonus:[3]
OfT. macrogonus var.pachanoi:[4]
| |
Trichocereus macrogonus,synonymEchinopsis macrogonus, is a species ofcactus found in Ecuador, Peru and Bolivia.[2] Two varieties are accepted as of September 2023[update]: var.macrogonus andvar.pachanoi. Plants contain varying amounts of the psychoactive alkaloidmescaline. They have been used both ritually and in traditional medicine from pre-Columbian times.Trichocereus macrogonus is one of a number of similar species that may be calledSan Pedro cactus. Indigenous names includeachuma andhuachuma, although these too may be applied to similar species.
The species has erect stems, 2.5–5 m (8–16 ft) tall, with branches generally with a diameter of 6–15 cm (2–6 in), occasionally more. At the base of the stem there are usually seven or eight ribs. Generally the species has relatively few ribs, typically six to eight, occasionally five or nine. The circular areoles are 6 mm (0.2 in) across, grey or dark brown, with needle-like spines, and are spaced more than 2.5 cm (1.0 in) apart. The number and length of the spines varies. InT. macrogonus var.macrogonus, older areoles may have up to 20, with three or four prominent, longer and more robust central spines up to 5 cm (2.0 in) long. In var.pachanoi, the older areoles may have only three to seven shorter and thinner spines. The spines are darker at the end. The flowers are carried mostly near the top of the stems. In total they may be up to 21 cm (8.3 in) long. Thetepals may be pale yellow or yellowish green, rarely pink. The small seeds are broadly ovoid, 0.9–1.1 mm (0.04–0.04 in) long.[5]
.jpg)
The first description asCereus macrogonus byJoseph zu Salm-Reifferscheidt-Dyck was published in 1850.[6] The specific epithetmacrogonus is derived from the Greek wordsmakros for 'large' andgonia for 'edge' and refers to the ribs of the species. Vincenzo Riccobono placed the species in the genusTrichocereus in 1909.[7] Heimo Friedrich and Gordon Douglas Rowley placed the species in the genusEchinopsis in 1974 asEchinopsis macrogona.
Many other names have been applied toTrichocereus macrogonus. The taxonomy of the species was clarified in 2012 by Sofía Albesiano and Roberto Kiesling. In particular, they sankTrichocereus peruvianus andTrichocereus pachanoi intoT. macrogonus, treatingT. pachanoi asT. macrogonus var.pachanoi. The number and size of the spines was regarded as a distinguishing feature of the two varieties, although this was noted to be a variable character, influenced by environmental conditions: cultivated plants develop more spines when moved to sunnier positions.[8]
As of 2023[update],Plants of the World Online accepted two varieties:[2]
| Image | Subspecies | Synonyms | Description | Distribution |
|---|---|---|---|---|
.jpg) | Trichocereus macrogonus var.macrogonus |
| longer spines (Spines of the older areoles 18−20, 3−4 of them prominent), blue green stems sometimes with notches, thicker stem diameter (16−20 cm)[9] | west and southPeru toBolivia[3] |
 | Trichocereus macrogonus var.pachanoi(Britton & Rose) Albesiano & R.Kiesling |
| small spines (spines of the older areoles 3−7, ca. 0.5−2 cm long), dark green to blue green stems, thinner stem diameter (6−11(−15) cm).[9] | southEcuador toPeru[4] |
Plants of the World Online regards the species as native toPeru,Ecuador, andBolivia, and introduced to centralChile,Colombia, mainland Spain and theCanary Islands.[2] However, plants are widely cultivated making the true origins of the species difficult to determine. It has been speculated that the original native distribution may only be the high valleys of Peru and perhaps also northwestern Bolivia.[8]
This species of cactus has been used by humans for several millennia. The oldest find was located in theGuitarrero Cave, in the Áncash region in Peru. In this cave, inhabited continuously since 8600 BCE, a high concentration ofT. macrogonus pollen from the oldest phase of human occupation has been detected, as well as some fragments of cactus, which would testify to the intentional introduction of this plant inside the cave.[10] Ritual uses of the species are depicted on pre-Columbian Peruvian ceramics and other archaeological objects, with one use dated to about 1300 BCE. Indigenous names includeachuma andhuachuma.[8]
Trichocereus macrogonus is one of a number of species native to the Andes that have been reported to contain the psychoactive alkaloidmescaline (reports may use various synonyms of the currently accepted names).[11] Another species isEchinopsis lageniformis. All the columnar species thought to be psychoactive have been called "San Pedro" in Spanish. Reported concentrations of mescaline vary widely, with causes suggested to include: taxonomic uncertainty leading to difficulties in identification; genetic differences between species and within populations; environmental factors, such as temperature and water availability, affecting plants during growth; and variations in laboratory techniques.[12]
Some studies have reported no mescaline content in wild-harvested Peruvian specimens ofT. macrogonus,[13] and in plants grown in Europe.[14] In those studies that have compared different species andcultivars, the concentrations found were very variable. In samples identified asEchinopsis pachanoi (i.e.T. macrogonus var.pachanoi), the lowest found was 0.4% of dry weight compared to 4.7% for a form on sale in traditional Peruvian shamans' markets.[12] The plants used by shamans are likely to be cultivars they have selected for their mescaline content.[8]Mescaline is not evenly distributed within single specimens ofE. lageniformis.[15]
Media related toTrichocereus macrogonus at Wikimedia Commons
Data related toTrichocereus macrogonus at Wikispecies